Our works directed to finding bioactive substances which have been carried out for past three years (1997-1999) are summarized as follows.1. Efficient and practical ring transformation of 6-eno-D-glycosides promoted by a catalytic amount of Palladium dichloride has been accomplished. The resulting cyclitols could be used for the synthesis of sugar-related bioactive compounds.2. Cyclophellitol and its 3-epimer which exhibit highly potent glycosidase inhibition could be synthesized efficiently.3. Novel synthesis of all diastereoisomers of Inositols and their phosphates such as IPィイD23ィエD2 and IPィイD24ィエD2 has been accomplished based on an application of the above transformation.4. Extremely efficient synthetic method for the preparation of sugar-sugar ortho esters has been found and their structures have been established by X-ray chrystallographic analysis and by MM2 computer calculation technique. Their selective reductions provided a new highly stereoselective glycosidation method.5. Application of the sugar ortho ester formation has made it possible in a short cut synthesis of voglibose, a potent glycosidase inhibitor.6. New decarboxylative glycosidation using sugar-sugar mixed carbonates has been extensively studied. Details of the reaction mochanism have also been examined7. Explitation of new synthetic technoloogy using chiral polymers has been also studies with starting design and synthesis of new type of polymers